New lignans from Phyllanthodendron dunnianum.

A new lignan phyllanins A (1) and a lignan phyllanins B (2) for which the absolute configuration was determined for the first time, along with four known lignans (3-6) were isolated from the branch and leaf extracts of Phyllanthodendron dunnianum. Their planar structures were mainly determined by a combination of 1D and 2D NMR, HRESIMS spectral analyses, and the absolute configurations of the compounds 1 and 2 were established by DFT GIAO 13C NMR and electronic circular dichroism (ECD) calculations. In addition, all these six lignans were firstly tested for the antibacterial activities against MRSA, Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli. Among these compounds, 2 and 5 showed potential antibacterial activities against MRSA and S. aureus with MIC values of 4 and 8 µg/mL, respectively.

Sesquiterpenes and α-pyrones from an endophytic fungus Xylaria curta YSJ-5.

Chemical investigation of the culture extract of an endophyte Xylaria curta YSJ-5 from Alpinia zerumbet (Pers.) Burtt. et Smith resulted in the isolation of eight previously undescribed compounds including five eremophilane sesquiterpenes xylarcurenes A-E, one norsesquiterpene xylarcurene F, and two α-pyrone derivatives xylarpyrones A-B together with eight known related derivatives. Their chemical structures were extensively established based on the 1D- and 2D-NMR spectroscopic analysis, modified Mosher's method, electronic circular dichroism calculations, single-crystal X-ray diffraction experiments, and the comparison with previous literature data. All these compounds were tested for in vitro cytotoxic, anti-inflammatory, α-glucosidase inhibitory, and antibacterial activities. As a result, 6-pentyl-4-methoxy-pyran-2-one was disclosed to display significant antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with minimal inhibitory concentration value of 6.3 µg/mL.

A Very Deep Graph Convolutional Network for 13C NMR Chemical Shift Calculations with Density Functional Theory Level Performance for Structure Assignment.

Nuclear magnetic resonance (NMR) chemical shift calculations are powerful tools for structure elucidation and have been extensively employed in both natural product and synthetic chemistry. However, density functional theory (DFT) NMR chemical shift calculations are usually time-consuming, while fast data-driven methods often lack reliability, making it challenging to apply them to computationally intensive tasks with a high requirement on quality. Herein, we have constructed a 54-layer-deep graph convolutional network for 13C NMR chemical shift calculations, which achieved high accuracy with low time-cost and performed competitively with DFT NMR chemical shift calculations on structure assignment benchmarks. Our model utilizes a semiempirical method, GFN2-xTB, and is compatible with a broad variety of organic systems, including those composed of hundreds of atoms or elements ranging from H to Rn. We used this model to resolve the controversial J/K ring junction problem of maitotoxin, which is the largest whole molecule assigned by NMR calculations to date. This model has been developed into user-friendly software, providing a useful tool for routine rapid structure validation and assignation as well as a new approach to elucidate the large structures that were previously unsuitable for NMR calculations.

Three new metabolites from the endophyte Fusarium proliferatum T2-10.

One new cyclopeptide, cyclo-(L-Trp-L-Phe-L-Phe) (1), one new 2-pyridone derivative, fusarone A (3), and one new natural indole derivative, ethyl 3-indoleacetate (4), along with six known compounds were isolated from the endophytic fungus Fusarium proliferatum T2-10. The planar structures of three new compounds were identified by spectral methods including 1D and 2D NMR techniques, and the absolute configuration of compound 1 was elucidated by Marfey-MS method. In addition, all compounds were evaluated for their cytotoxic and antibacterial activities in vitro. Compound 2 showed remarkable cytotoxic activities against two human hepatoma cell lines SMMC7721 and HepG2 with IC50 values of 5.89 ± 0.74 and 6.16 ± 0.52 µM, and showed moderate antibacterial activities against Staphylococcus aureus and Enterococcus faecalis with MIC values of 7.81 and 15.62 µg/mL, respectively.

Betulinaldehyde exhibits effective anti-tumor effects in A549 cells by regulating intracellular autophagy.

It is of great significance to find new effective drugs for an adjuvant therapy targeting lung cancer to improve the survival rate and prognosis of patients with the disease. Previous studies have confirmed that certain Chinese herbal extracts have clear anti-tumor effects, and in our preliminary study, betulinaldehyde was screened for its potential anti-tumor effects. The current study thus aimed to confirm the anti-tumor effect of betulinaldehyde, using in vitro experiments to explore its underlying molecular mechanism. It was found that betulinaldehyde treatment significantly inhibited the viability, proliferation, and migration of A549 cells in a dose-dependent manner. In addition, betulinaldehyde inhibited the activation of Akt, MAPK, and STAT3 signaling pathways in A549 cells in a time-dependent manner. More importantly, betulinaldehyde also decreased the expression level of SQSTM1 protein, increased the expression level of LC3 II, and increased the autophagy flux in A549 cells. The pretreatment of A549 cells with the autophagy inhibitor, 3-methyladenine, could partially negate the anti-tumor effects of betulinaldehyde. These findings suggest that betulinaldehyde could significantly inhibit the oncological activity of A549 cells by regulating the intracellular autophagy level, making it a potentially effective option for the adjuvant therapy used to treat lung cancer in the future.

Two new chromone derivatives from the rhizosphere soil fungus Ilyonectria robusta.

Two new chromone derivatives (1 and 2), and two known compounds (3 and 4) were isolated from the rhizosphere soil fungus Ilyonectria robusta. Their planar structures and absolute configurations were determined by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculations. Additionally, all the isolated compounds were evaluated for their antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli, but no obvious activity was observed at a concentration of 128 µg/mL.

Pseudocercones A-C, three new polyketide derivatives from the endophytic fungus Pseudocercospora sp. TSS-1.

Chemical investigation of an EtOAc extract of the endophytic fungus Pseudocercospora sp. TSS-1 led to the isolation of three new polyketide derivatives, including one benzophenon derivative (1), two spirocyclic polyketides (4 and 5), along with four known compounds (2, 3, 6 and 7). Their structures and the absolute configurations were characterized by means of NMR, HRESIMS, 13C NMR and theoretical electronic circular dichroism calculations. Furthermore, all compounds were evaluated for their antibacterial activity against four microbial pathogens (Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa and Escherichia coli), and compounds 1, 2, 3 and 5 displayed significant selective antibacterial activity against S. aureus with MIC values ranging from 3.9 to 7.8 µg/mL.

Reassignment of the structures of pestalopyrones A-D.

Pestalopyrones A-D are four unusual tricyclic pyrone derivatives with flexible chiral structures, isolated from the endophytic fungus Pestalotiopsis neglecta S3. The full elucidation of their structures was a challenging task, and remained unsolved in the original article. Herein, the relative configurations of pestalopyrones A and pestalopyrones B were unambiguously assigned by detailed analyses on spectroscopic data and GIAO 13C NMR calculation method with sorted training sets (STS). The planar structures of pestalopyrones C and pestalopyrones D were revised by reinterpretation of their reported spectroscopic data, and then their relative configurations were deduced by STS GIAO 13C NMR calculation and NOE analysis. The absolute configurations of all the mentioned compounds were determined by the comparison of their experimental and calculated ECD curves.

Identification of a new natural biflavonoids against breast cancer cells induced ferroptosis via the mitochondrial pathway.

Breast cancer is one of the major malignant tumors in females, and currently, recurrence and metastasis are the main obstacles preventing effective breast cancer treatment. Biflavonoids of secondary metabolites from plants are excellent anticancer agents to fight sensitive and resistant breast cancer cell lines. In this study, six C-3'-C-6″ biflavonoids, including one new robustaflavone A (1, RF-A) and five known robustaflavone derivatives (2-6), were isolated from Selaginella trichoclada for the first time. We aimed to evaluate the inhibitory effects of compounds 1-6 against human breast cancer MCF-7 cells. Among the six compounds, RF-A showed the strongest activity, decreasing cell viability with an IC50 value of 11.89 µΜ. Furthermore, RF-A strikingly induced MCF-7 nonapoptotic cell death through ferroptosis by enhancing the expression of VDAC2 channels and reducing the expression of Nedd4 E3 ubiquitin ligase, leading to lipid peroxidation and ROS production. The results suggested that RF-A has potential as a novel breast cancer treatment through its regulation of the mitochondrial VDAC2 and Nedd4 pathways.

New cytotoxic biflavones from Selaginella doederleinii.

Three new biflavones, apigenin-(3',8″)-chrysin (1), (2S)-2,3-Dihydroametoflavone 5,4'-dimethyl ether (2), and (2S)-5″,7″-Dihydroxy-2″-phenoxychromonyl-(4'″,3')-naringenin (3), together with seven known biflavones (4-10) were isolated from the 75% EtOH extract of Selaginella doederleinii. The structures of new compounds were established by application of spectroscopic methods, including 1D and 2D NMR, HRMS, and CD measurements. In addition, all new compounds were evaluated for their cytotoxic potential against three human cancer cell lines A549, MCF-7, and SMMC-7721 in vitro. Compound 2 exhibited potent cytotoxic activity with IC50 values ranging from 6.35 to 10.18 µM.

Lignans and phenolic constituents from Eucommia ulmoides Oliver.

Two new lignans, noreucol A (1) and (+)-epicycloolivil (2), along with seven known compounds (3-9) were isolated from the aqueous extract of Eucommia ulmoides Oliver. Compound 1 was a new norlignan and 2 was an epimer at C-7 of (+)-cycloolivil (3). Their structures were elucidated by spectroscopic methods, and the absolute configurations of new compounds were determined by conformational analysis and DFT theoretic electronic circular dichroism spectra calculations. In addition, the neuroprotective activity of compounds 1-3 against glutamate-induced HT-22 cells injury were evaluated, and only compound 1 exhibited moderate effect at the concentrations ranging from 10 ∼ 50 µM.

Two new biflavanoids from Selaginella trichoclada Alsto.

Two new robustaflavones, (±)-trichocladabiflavone A (1) and uncinatabiflavone E (2), along with seven known biflavanoids (3-9) were isolated from the 70% EtOH extract of Selaginella trichoclada. Their structures and absolute configurations were established by extensive spectroscopic and circular dichroism (CD) analyses. Compound 1 was resoluted into optically pure enantiomers (+)-1 and (-)-1 by chiral-phase HPLC. Moreover, compounds 1 and 2 exhibited moderate cytotoxicity against A549 and HepG2 human cancer cell lines.

Triterpenoids with antiproliferative activities from the twigs and leaves of Melaleuca linariifolia.

One new pentacyclic triterpenoid, urs-12,16-dien-3-one (1), together with twelve known pentacyclic triterpenoids (2‒13), were isolated from the twigs and leaves of Melaleuca linariifolia. Their structures were characterized by their 1D- and 2 D-NMR spectra analysis and mass spectra studies. Furthermore, all isolated compounds were tested the inhibitory effect on proliferation of six human cancer cell lines in vitro, including NCI-H441, NCI-H460, A549, SKOV3, hela, and caki-1 cells. Among them, compounds 3, 5, 7, 9, 12, and 13 exhibited moderate antiproliferative activities with IC50 values ranging from 3.85 to 33.31 µM.

Seladelicatulasine A-G, C27 steroidal glycosides with cholinesterase inhibitory activities from Selaginella delicatula.

Seven undescribed C27 steroidal glycosides, Seladelicatulasine A-G, including six cholestanol glycosides and one spirostanol glycoside, were isolated from Selaginella delicatula. Their structures were elucidated by 1D/2D NMR spectra and HRESIMS analyses. The absolute configurations of the sugars were determined by enzymatic hydrolysis and GC/MS analyses. These cholestanol glycosides were isolated from the family Selaginellaceae for the first time. Seladelicatulasine F is characterized as a rare B-5,6-secosteroid. In addition, all the compounds were evaluated for their inhibitory activities against cholinesterase (AChE/BChE) and monoamine oxidase (MAO-A/MAO-B). These steroidal glycosides displayed selective inhibition activities on cholinesterase. Seladelicatulasine A, B and E inhibited the AChE activity with IC50 values of 0.31, 0.09, and 0.04 µM, respectively. Seladelicatulasine A and F showed the strongest inhibition activity on BChE with IC50 values of 0.37 and 0.65 µM, respectively.

Two New Abietane Diterpenoids from Selaginella moellendorffii Hieron.

Two new abietane diterpenoids, (3S,5R,10S)-3-hydroxy-12-O-demethyl-11-deoxy-19(4→3)-abeo-cryptojaponol, 12,19-dihydroxyabieta-8,11,13-trien-7-one, were isolated from Selaginella moellendorffii Hieron., together with one known abietane diterpenoid and four known tetracyclic triterpenoids. Their structures were characterized by their 1D- and 2D-NMR, ECD and mass spectral studies. All compounds were tested for their inhibitory effects on proliferation of three human cancer cells (human non-small-cell lung carcinoma cell lines A549 and human breast adenocarcinoma cell lines MDA-MB-231 and MCF-7) in vitro. Among them, three compounds displayed modest cytotoxic activities against the above three human cancer cell lines with IC50 values ranging from 16.28 to 40.67 µM.

Palhinosides A-H: Flavone Glucosidic Truxinate Esters with Neuroprotective Activities from Palhinhaea cernua.

Palhinosides A-H (1-8), new flavone glucosidic truxinate esters, including ß-truxinate and µ-truxinate forms, were isolated from Palhinhaea cernua. Their structures were elucidated by extensive spectroscopic methods and chemical analyses. The flavone glucoside cyclodimers possess a unique cyclobutane ring in their carbon scaffolds. Compounds 2-7 represent three pairs of stereoisomers (2/3, 4/5, 6/7). The protective effects of 1-8 against the damage of HT-22 cells induced by l-glutamate were evaluated, and compounds 4 and 5 showed better neuroprotective effects than the positive control, Trolox.

Pictalignans D-F, three new neolignan derivatives from Selaginella picta.

Three new neolignan derivatives (1-3), together with three known isolariciresinol derivatives (4-6) were isolated from Selaginella picta. Their structures were elucidated by spectroscopic methods (1D/2D NMR, HRESIMS and CD). All isolated compounds were assayed on the neuroprotective activity against the injury of HT-22 cells induced by L-Glutamate in vitro. All compounds displayed potent protective effect on HT-22 cells.

Two new anthraquinone derivatives and one new triarylbenzophenone analog from Selaginella tamariscina.

Two new anthraquinone derivatives, selaginones A (1) and B (2), and one new triarylbenzophenone analog, selagibenzophenone B (3), were isolated from Selaginella tamariscina (Beauv.) Spring. Their structures were established by 1D-, 2D-NMR and HR-ESI-MS data. Compounds 1 and 2 represent the uncommon examples of aryl substituted anthraquinone derivatives. Especially, compound 2 is a unique anthranone with exceptional structural feature, in which a p-hydroxyphenyl moiety is attached to the C-10 position. Compound 3 is the second naturally occurring triarylbenzophenone and showed moderate activity against SMCC-7721 and MHCC97-H cell lines with IC50 values of 39.8, 51.5 µM respectively.

Anti-cholinesterase activities of constituents isolated from Lycopodiastrum casuarinoides.

Phytochemical investigation of the ethyl acetate extract of Lycopodiastrum casuarinoides (Spring) Holub (Lycopodiaceae) led to the isolation of nine compounds, including two new serratene triterpenoids, serrat-14-en-3α,21α-diol (1), 26-nor-8-oxo-21-one-α-onocerin (6), one new abietane diterpenoid, lycocasuarinone A (7), one new sesquiterpene acid, 7, 9-diene-1,4-epoxy-2-hydroxy-10-carboxylic acid (8) and one new chromone derivative, 5,7-dihydroxy-2-methyl esterchromone (9), together with four known serratene triterpenoids (2-5). Abietane diterpenoid (7) and sesquiterpene acid (8) from Lycopodiastrum casuarinoides are reported for the first time. Their structures and stereochemistry were unambiguously elucidated by spectroscopic analysis and comparison with known ones. All the compounds were tested for acetylcholinesterase (AChE) and butyrocholinesterase (BuChE) inhibitory activities. Bioactivity assays revealed that compound 6 exhibited the most potent AChE inhibitory effect.

Application of the Ethyl Acetate Extract of Cichorium as a Potential Photosensitizer in Photodynamic Therapy Induces Apoptosis and Autophagy in Colorectal Cancer Cell Lines via the Protein Kinase R-Like Endoplasmic Reticulum Kinase Pathway.

The present study aims to evaluate the effect of the ethyl acetate extract of Cichorium (EAEC) as a novel photosensitizer in photodynamic therapy (PDT) of colorectal carcinoma (CRC) HCT116 and SW620 cells. The absorption and fluorescence spectra of EAEC were measured using a UV-vis spectrophotometer and fluorescence spectrophotometer, respectively. EAEC-induced reactive oxygen species (ROS) production in HCT116 and SW620 cells was detected using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and glutathione/glutathione disulfide (GSH/GSSG). The photo- and dark toxicities of EAEC were estimated using the Cell Counting Kit-8 (CCK-8) assay. Cellular uptake and localization of EAEC were detected by confocal laser fluorescence microscopy. Annexin V-FITC/PI staining, Western blotting and immunofluorescence staining were used to assess apoptosis and autophagy. The antitumor activity of EAEC was confirmed in a xenograft model. Finally, effects on the PERK pathway were verified using qRT-PCR and Western blotting. EAEC displayed absorption and fluorescence emission peaks at 660 nm and 678 nm, respectively. EAEC induced ROS production in CRC cells. Assessment of dark toxicity showed that treatment with EAEC alone induced little cytotoxicity in CRC or normal cells but that EAEC-PDT induced significant photocytotoxicity in CRC cells in a time- and dose-dependent manner. After cellular uptake, EAEC was located in the mitochondria. Treatment with EAEC-PDT reduced xenograft tumor size. Further evaluation suggested that activation of the PERK pathway mediates these effects, as the apoptotic rate and autophagy flux increased markedly after EAEC-PDT. EAEC, a natural photosensitizer extracted from Cichorium, displays potential utility in PDT of CRC by targeting the PERK pathway.